As a prior art, a portable terminal according to Non-patent Document 1 is mentioned which is capable of receiving a ground-wave digital broadcast. In order to obtain a great electric-field strength, the portable terminal according to Non-patent Document 1 executes a diversity reception, using both a conventional cellular-phone antenna and an earphone antenna by the code of an earphone used in a portable radio or the like.
In addition, the art of guiding a user to a position in which the electric-field strength is great is proposed in Patent Document 1. In a portable communication terminal according to Patent Document 1, using a geomagnetic sensor or a gyro sensor, an electric-field strength and the direction of a directional antenna are displayed on the screen of the portable communication terminal. This leads the user to the great electric-field strength direction.
The art according to Non-patent Document 1 has a disadvantage in that if no earphones are used, a sufficient electric-field strength is not obtained so that a television broadcast cannot be viewed. In the art according to Patent Document 1, a television broadcast cannot be viewed while searching for the direction in which a great electric-field strength is obtained. Besides, the art according to Patent Document 1 has another disadvantage in that a user is difficult to notify of the direction where an enough electric-field strength to watch television can be obtained.    Patent Document 1: Japanese Patent Laid-Open No. 2001-36320 specification    Non-patent Document 1: “Mechanism of a mobile phone which enables a user to watch terrestrial digital broadcasting”, an article in the August 2004 issue of the Nikkei Network, on the Internet <URI:http://itpro.nikkeibp.co.jp/free/TIS.keitai/20040913/149826/index.shtml>.